by Bob Beranek
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The other day my friend and colleague Carl Tompkins from Sika gave me a call questioning a term found in the 2013 NAGS Catalog. On the 2013 Honda Odyssey, NAGS refers to asymmetrically strengthened glass (ASG). As soon as I learned how to spell it, (thanks spell check), I decided to look it up and see what it was.

What I found was a patent on the idea from Shandon Dee Hart, patent number US20130127202 A1. In the patent description it is described as a glass assembly of components that when put together deliver a product that has uses in many different industries. In the patent, Mr. Hart uses the automotive windshield as a practical example.

The ASG is basically an outside piece of glass that is harder than the inside piece of glass and bonded together with a laminant of unspecified material. The harder outside lite is more impact resistant, while the inside lite allows for impact absorption similar to the current windshield we know today.

The patent mentions numerous ways the outside lite can be hardened, such as films applied, thicker glass, added ingredients in the batch or processes to make the glass harder—similar to how tempered glass is hardened. At this point, I do not know what Honda has done to its glass to meet the meaning of this term but I’m hoping to do more research and let you know.

What does this mean for the future of auto glass replacement? The purpose of the harder outside layer is for impact resistance, and if it works, there will be fewer windshields to be put in. However, the jury is still out on ASG when it comes to break resistance and safety to the occupants.

ASG may be resistant to blunt force impact, but what about a sharp-edged rock travelling at 60 mph? Will the advanced glass design be resistant to that sort of force? It should be interesting to see the data after a few years of tracking the results. Will the cost increase in glass manufacture justify the use of the new types of glass design? Again, time will only tell.

Then I asked myself, does this added feature make the glass more or less safe? That remains to be seen. It could be argued that the windshield with a harder outside lite may cause more injury because the glass will not give as much as it did with a softer outside lite. One of the purposes of the lamination is to cushion the body in a collision and absorb some of the trauma of impact. If the outside lite is harder, the body will not be cushioned as much so injuries could be worse.

Whatever the results of this experiment with advanced glass design yields, we have to be prepared to replace it in the same safety conscious way as we do today. Because, let’s face it, it will break.

Comments (8)

  1. […] TODAY’S BLOG: What is Asymmetrically Strengthened Glass? […]

  2. Glasseye said on 06-09-2013

    This is reminds me of a windscreen that was developed by Triplex and fitted to the Rover SD1 sold in the states as the Rover 3500 in the 1975/85 period. The inner layer of the laminated glass was toughened in such a way that if there was high impact the glass shattered to a powder, reducing incidence of laceration. It was called the Triplex 10/20. I believe it was discontinued because of the high cost of manufacture.

  3. daniel said on 06-09-2013

    I remember I had such a situation back in late nineties, with a TRIPLEX windshield on a Rover Vandenplas. The inside surface was covered with some kind of film, severely damaged by the owner while trying to clean the ice condensed after a stiff night frost.

  4. Tim said on 06-09-2013

    I’ve been putting in ASG glass in big trucks since they came out in 2007. The trucking companies that I have putting them in have seen a longer lasting glass. Most that I replace are usually just pitted up so bad, that is why they change them, not because they are broke. So in my opinion, yes the glass will last longer, sure the cost is more, but if they last longer, isn’t that a win for the customer.

  5. Carrie L. Cox said on 06-09-2013

    Agree with Tim’s comments on ASG glass. The ASG w/s costs more but most of our fleets think it is worth it since any down time on their rigs cost them more $$$ in the long run. Our NOVUS Repair Techs say the AGS w/s repairs just fine. The NAGS part numbers we install the most are DW1665 / DW1710. Always learn alot from your columns, thank you Bob Beranek !

  6. old timer again said on 06-09-2013

    How many of you have worked in manufacturing?
    The heat source is below the outside lite so as a result it cools stronger.
    That is why the inside lite is always softer.
    Some claim that there is a slight grain pattern in the glass.
    When the grain pattern is purposely crossed between the two lites you have
    an asymmetrically strengthened windshield.
    This in no way means that the windshield will resist stone damage any better.
    Might help you in a roll over though.

  7. old timer again said on 06-09-2013

    I remember many years ago when the 1st HUD w/s’s were made. I was told in a meeting that they were so expensive because they were inspected 10x’s over to make sure that
    the area above the steering wheel was perfect and had no visual imperfections.
    When I asked at what point in the production process the silkscreen HUD was applied to the glass you could have cut the air with a knife.A priceless moment.
    Don’t always accept the experts explanation.

  8. ALAN MAUPIN said on 06-09-2013

    WELL THEY ARE A MESS. IT HAS BEEN OUT FOR A COUPLE OF YEARS. LET ME EXPLAIN. THEY ARE MANUFACTUED BY PILKINGTON FOR THE OEM AND THEY ARE ALL DELAMINATING AS WE SPEAK. WE HAVE REPLACED MORE THAN A DOZEN FOR MY LOCAL HONDA DEALER THEY ARE STILL GETTING THE OEM WINDSHIELD WHICH IS STILL MADE BY PILKINGTON AND FITS TERRIBLY BECAUSE IT IS SO WAVY. MAYBE BOB IS ON TO SOMETHING IF THE INNER LAYER IS SOFTER MAYBE IT IS FLEXING A LITTLE WITH THE BODY MOVEMENT WHILE THE OUTSIDE IS NOT. OR THE CHEMICAL MAKE UP IS CAUSING THEM TO COME APART BECAUSE OF BONDING ISSUES. IF AT ALL POSSIBLE STAY AWAY FROM THE PILKINGTON WINDSHIELDS ALTHOUGH I THINK THEY ARE THE ONLY COMPANY MAKING IT.

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